Removing center wall under W truss system 3

[ndnalibi]

Hello,

I have a house with a W truss system that was built in the early 70s. There is a center wall that I want to remove between the kitchen and living room and have been told that it is not a problem because of the trusses. I can see from the framing that it is not a load bearing wall (no headers over the doorway).

Due to the age of the house, should I be concerned that the roof may sag after removing the wall?

Would it be appropriate to add triangle plywood plates to attach the bottom cord to the outside web? Is there a better place where failure may occur?

Thank you in advance for your time in answering my question.

Bill

 

[ztengguy]

Take it out if its not load bearing??? Why the question?

 

[ndnalibi]

I am not a structural engineer, but my understanding is that even if a wall is not load bearing, over time the overall structure of the house may settle upon a wall like this. Once removed, there may be some additional settling.

Is this not correct?

 

[RHTPE]

Just a quick consideration of your situation - if the interior wall was framed after the trusses, roof sheathing & roofing were installed, then I would expect little deflection after removing the interior wall. However, if the interior wall was framed before the trusses were set, it is possible that the wall prevented deflection of the trusses from the dead load of the trusses, sheathing & roofing. In that case, some additional deflection after removing the interior wall is possible.


Ralph
Structures Consulting
Northeast USA

 

[Ussuri]

Be careful. Buildings do move over time so you are correct that was not originally a lod bearing wall may now be providing that function.

Also your wall may not be transferring vertical loads, but it may be serving another purpose, such as lateral stability to your house or a return to adjacent wall panel.

I would suggest getting it looked at by a professional. You wouldn't want your house to collapse now would you?

 

[MiketheEngineer]

Done all the time if truly non load bearing and it probably is not. If the house width is say 30' or less and the trusses are made from decent grade 2x4's and you don't live in a high snow zone - then you are probably just fine. Biggest problem is going to be repairing the drywall ceiling so it looks OK.

BTW - in those days the trusses were anchored with two maybe three nails. I would suggest that you might want to add "hurricane" clips at the ends holding the trusses to the exterior walls. This is often where we see failures during a wind event.

 

[ndnalibi]

Mike - no drywall - it's a rehab and all the drywall has been ripped out.

It's also a fairly small 3 bed 1 bath ranch - brick exterior.

Thanks for the advise, everyone.

 

[RHTPE]

ndnalibi - Another thought. If the floor supprting the interior partition spans from foundation to center beam to foundation and the floor joists bear on top of the center beam, the wood shrinkage over time has probably negated any real support of the roof trusses.

I suspect that you'll be okay. But do consider Ussuri's point about the overall lateral stability of what will remain and Mikethe Engineer's point about proper anchorage of the roof trusses to the bearing walls. If you have the drywall all removed, now would be the ideal time to upgrade the wind load path from roof truss to foundation.

Ralph
Structures Consulting
Northeast USA

 

[ToadJones]

Having framed many houses like you are describing, I can tell you that more often than not, the bottom chord of the truss doesn't even hit the partitions near the center of the home.
The truss sometimes has a slight camber in the bottom chord ....whether intentional or unintentional. Sometimes it can be the other way around where the partitions seem "too tall" b/c the bottom chord of the truss has a POS 2x4 that is warped.
Still more, sometimes the beam in the basement is too damn high and if it is a slab, 99.9999% the concrete is no where near flat and the walls are up & down all over the place.
At any rate, if the partition is just that, a partition and you have exterior load bearing trusses, "then tear that wall down"

 

[StructuralEd]

If the trusses are sitting hard on the wall I would expect deflection once you take the wall out.

If you are effectively doubling the span, there will be significant deflection at a point that there was zero deflection.

Even though the truss may be structurally adequate for the full span, it was being held up by the wall.

Warn the client so you are not responsible for the ensuing distress to the finish materials.

 

[msquared48]

I am about 99% sure that it is not, but make sure that the wall is not a shear wall, regardless of any bearing.

If this wall extends to the roof diaphragm, then it is a shear wall. If it extends to a floor structure above, it could be, but probably not. Being from the '70's you most likely will not find any holddowns either.

Mike McCann
MMC Engineering